It reads
(the words in '' are redacted, empty lines have been deleted for brevity):
"
'Site Name'
The following surveys are available:
No available surveys
Please contact 'Full Name' ( 'email address' ) for further assistance.
Choose another language
English - English
[LimeSurvey Survey Software]
The Online Survey Tool - Free & Open Source
"

Could this page be made completely invisible (replace by a blank page for security)?
Could the 'Full Name' and the 'email address' be left out (spam).
Any other option?

This needs to be adapted in the survey template that is used as default for the installation (I am not quite sure why this is part of the survey template, and not of the administration template, but I guess that comes from the fact, that for a long time, there was no administration template).

So ideally you go to the template editor, make a copy from the template that you would like to use as the base template and then choose at the top right corner where it says "Screen" the view "Survey list page". Then on the left you choose the template file called "surveylist.pstpl" and adapt it to your liking. If you want to change colors, etc. you can do it via CSS.